- 1). Check that your mousetrap is not armed. Turn it upside down and use the ruler to help you mark four dots on the base of the trap, one at each corner. Drill shallow guide holes into each mark.
- 2). Measure the width of the trap, plus the combined width of two of the wheels. This will give you the length of the front axle. The rear axle should be the width of the trap plus an inch. Cut the wooden dowels to these lengths. You may need to shorten them a little later on, but it's easier to cut away more of the dowel than it is to add length if you cut too much.
- 3). Screw the four eyelets into each guide hole. The holes in the eyelets should face outwards to the side of the trap. Slip the dowel axles into the holes.
- 4). Cut four small circles of card. Make a hole in the exact center of each that is just big enough to take the dowel. Glue these to the middle of each CD, one on either side, making sure they are exactly centered. Allow to dry. When completely dry, fix the CD wheels to the rear axle and glue in place. You may want to support them with modelling clay while the glue sets so that they dry straight. Fix the toy wheels to the front axle.
- 5). Measure off about 9 or 10 inches of string or cord. Tie one end securely to the arm bar of the mousetrap. Tie the other end around the rear axle. There should be no slack between the raised arm bar and the axle; if the string isn't taut you can trim it. Set the trap, lowering the arm bar. Handling the mousetrap very carefully, wind the string around the axle by spinning the back wheels in reverse.
- 6). Set the car down on the floor (a hard floor is best) and use the ruler to spring the trap. Your car should race across the floor. You may need to make a few adjustments to get it running just right.
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